1. Field of the Invention
The field of the invention is a device for adjusting the string tension on a guitar or other stringed musical instrument.
2. Problems in the Art
Stringed musical instruments possess one or more tensioned strings stretched across a sounding board or other main body of the instrument which amplifies the audible vibration of the string. One end of the string is anchored at one side of the main body or sounding board and stretched across a bridge, the string then strung across the sounding board, and along an elongated neck portion attached to the main body. The other end of the string is then anchored at the end of the neck away from the main body to devices which permit individual or group adjustment of the string tension. At variously determined intervals along the neck portion are situated a plurality transverse ridges which underlie the plurality of strings. The strings vibrate due to physical manipulation, usually plucking or strumming with either fingers or an implement.
The sound emitted from a vibrated string is termed its pitch and is determined by the relationship of the tension of the string, its mass per unit length (which is a function of the string's diameter and composition), and the length of the string available for vibration, i.e. the effective length. The effective length of the string is the distance between a first anchor, called the bridge, attached at the head of the main body of the fretted stringed instrument, and a second anchor, called the string nut, attached at the far end of the neck. Typically the strings ride over a saddle which is immediately adjacent to the bridge. The effective length in which case then starts at the saddle and terminates at the distal end of the neck. At the distal end of the neck is the second string anchor, the string nut, through which all of the strings pass and contact immediately before they are attached to the tuning pegs. Various stringed instruments may not possess all of the aforementioned features but their principle of operation is similar.
A common method for changing the pitch is to temporarily shorten the effective length of the strength by pressing down upon one of the transverse ridges (frets). Since the only other variable that affects pitch that can be easily modified is tension, numerous innovations have sought to provide means with which to modify the tension to varying degrees of simplicity.
A popular innovation is the B-Bender which adjusts the tension on the B-string of guitars. Several variations on the B-Bender exist but the drawback is that only one string may be tensioned since the device is installed to affect only a single string and is not positionable so that different strings may be tensioned.
The most well known string bending device is described by U.S. Pat. No. 2,741,146, Tremolo Device for Stringed Instruments, by C. L. Fender (Apr. 30, 1954). The device is intended to allow the player of the instrument to vary the tension on a string by manipulation of a tremolo control arm which fits in the players palm and is incorporated in the bridge. The drawback to the Fender invention is that stretches all of the strings at once preventing the pitch adjustment of a single string while the permitting the remaining strings to be unaffected.
U.S. Pat. No. 3,479,917, Multiple Lever Manual Tone Changer For Guitars by Zitnik et al. (Nov. 25, 1969), describes using finger or palm operated levers to adjust the tension on guitar strings. Multiple strings can be affected only if multiple levers are installed.
Another innovation to adjust the tension of a guitar string is described in U.S. Pat. No. 5,567,897, Guitar Pull String Device, by McEwen (Oct. 22, 1996). McEwen describes a string tension adjustment device for electric guitars. The string tension is adjusted by means of a pull arm to which a shoulder strap is attached so that when the guitarist desires to activate the string tension adjustment device, he simply presses down on the neck of the guitar to pull the pull arm which in turn pulls a linkage mechanism that pulls or “bends” the string of the guitar that is coupled with the device. This method of tensioning a string is markedly different from the present invention in that it is not possible to change which string is affected while actually playing the instrument. Additionally, the present invention deforms the string while the McEwen invention stretches the string, this is expected to play a significant role in extending string life.